The objective is to develop the capability to design and build specialized biomedical computing systems that make use of Commercially available and custom designed Very Large Scale (VLSI) integrated circuits, and to make this technology available as part of the Washington University Resource for Biomedical Computing. Four specific goals are: 1) to acquire VLSI design tools and techniques from others, and to augment and integrate them into a design aid system useful for biomedical applications; 2) to carry out research in the design and use of asynchronous modules realized in VLSI, as a means to facilitate the building and modification of experimental systems; 3) to study use of the new tools in promising application areas through collaboration with biomedical researchers at Washington University; and 4) to identify and remove the obstacles to easy and widespread use of our new capabilities by biomedical scientists. A difficult but very important objective is to make the introduction of VLSI technology possible into the early and middle, as well as the late stages of important biomedical research projects that require large amounts of accessible computation. Current examples of such projects include maximum-likelihood estimation of images from advanced PETT (Positron-Emission Tomography) instruments, and high-accuracy calculation of dosage in radiation treatment planning. Accomplishing this objective requires rapid specification, design, and fabrication of specialized chips and systems, and very careful attention to the integration of specialized processors into flexible and rapidly evolving research computing systems. Our work to date has made excellent progress in facilitating chip specification and design; the major thrust during the current period of research is solving the problems of rapid and flexible system evolution.